Merge_sort, a problem with comparison

#include "stdafx.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include "myfile.h"
using namespace std;
myfile f;
/* merge is the auxilery function of mergsort */
int merge(int a[],int p, int q, int r)
{
    f.print("\nmerge:");
    f.print(a,p,r);
    int n1=(q-p);
    int n2=(r-q);
    int * al=new int[n1];
    int * ar=new int[n2];
    for(int i=0;i<n1;i++)
	al[i] = a[p+i-1];
    for(int j=0;j<n2;j++)
	ar[j]=a[q+j];
    //al[n1+1]=-1;
    //ar[n2+1]=-1;
    int i=0;
    int j=0;
    for(int k=p;k<r;k++){
	if (al[i]<=ar[j]){
		a[k] = al[i];
		i++;
	} else {
		a[k]=ar[j];
		j++;
        }
	f.print(a,r);
    }
    return 0;
}

/* mergesort sorts an array a[0..l-1] acording to MERGESORT algorithm */
int q=0;
int mergesort(int a[],int p,int r){	
    f.print("\nmergesort:");
    f.print("\np=");f.print(p);	
    f.print("   q=");f.print(q);
    f.print("   r=");f.print(r);
    /*f.print("\n");*/f.print(a,r);	
    if(p<r){
        q=abs((p+r)/2);			
        mergesort(a,p,q);	
        mergesort(a,q+1,r);
	merge(a,p,q,r);
    }
    return 0;
}

/* getarraylenght gets the length of the array */
int getarraylength(){
	cout<<"\nPlease enter Array length ::: ";
	int l; cin>>l;	
	return l;
}

/* gettarray gets an array and pass it to be sorted */
int getarray(){
	int l=getarraylength();
	int * a = new int[l];
	cout<<"\nPlease enter array numbers ::: ";
	int i=0;
	for(i=0;i<l;i++){
		cout<<"\na["<<i<<"] ::: ";
		cin>>a[i];
	}		
	f.print(a,l);
	mergesort(a,0,l-1);
	return 0;
}
int _tmain(int argc, _TCHAR* argv[])
{
	cout<<"Main...\n";
	getarray();
	myfile f;
	/* hold the screen */ cout<<"\nEnter any key to continue ::: ";char ch;cin>>ch;
}